1. Field of the Invention
The invention is directed to a separating piston for a vibration damping system, especially hydropneumatic vibration dampers or self-pumping level regulation devices, with a cylinder which is filled partly with damping fluid and partly with pressure gas and a separating piston which is arranged in the cylinder and divides the pressure gas space from the fluid space in a sealing manner by means of a seal. The separating piston is guided by a guide in the cylinder.
2. Discussion of the Prior Art
Separating pistons for hydropneumatic shock absorbers are already known (e.g., DE-PS 32 31 135). In separating pistons of this kind, the separating member located between the pressure gas space and the fluid space is constructed as a floating piston which serves to calm the surface of the fluid during operation of the damper. The pressure gas space is arranged in the vicinity of the lower work space filled with damping fluid and serves essentially to support the compression stage. The separating piston is used as a separating element. In the rebound stage of a vibration damping system, the pressure increases in the upper work space depending on the volume flow present at the pre-adjusted tension valve of the damping piston, whereas, in the compression stage, the pressure in the upper work space correspondingly decreases depending on the volume flow present at the pre-adjusted compression stage valve of the damping piston. The absolute pressure at the separating piston on the side of the gas space is virtually identical to that on the side of the fluid space. Vibration dampers which work on this principle are known as classic single-tube gas pressure dampers.
It is disadvantageous in these known single-tube gas pressure dampers that the separating piston can only be used for defined damping piston/piston rod diameter combinations. One such diameter combination which is known to be adequately dimensioned has, for example, a damping piston diameter of 36 mm combined with a piston rod diameter of 11 mm. A sufficient service life and resistance to wear is achieved over a broad temperature spectrum with this combination.
With less favorable diameter combinations, especially where the diameters of the piston rods are larger while retaining the previous diameter of the damping piston, the sealing element used in the separating piston can no longer adequately seal the damping fluid relative to the pressure gas space. As a rule, an impermissibly large amount of damping fluid is determined in the gas space in connection with an absolute change in position of the separating piston in the direction of the damping piston. This leads to total failure when the basic geometric data of the vibration damper are unfavorable, for example, in that the damping piston becomes permanently caught on the separating piston with low reserves. This substantially reduces the life expectancy of the vibration damper.